I have a question about the Gerber file format for PCB prototype. The CAD program I am using is a DOS version and generates Gerber files in the RS-274-D format. However, ALLPCB require the Gerber files in the RS-274-X format. How can I convert the gerber files format from RS-274-D to RS-274-X?
The gerber format is an open format, thus the description should be freely available.
Why didn't you do a simple internet search?
Even wikipedia has a good description and links to the specification.
There couldn't be a better source of information than the specification.
You start by dumping the DOS program and get something from at least the early 2000's. The difference between RS-274-D and RS-274-X, is that the -D version requires an aperature table that must be manually input by the vendor. The -X version has the aperatures embedded in the encoding. It is easy to see why ANY PCB manufacturer would balk at any -D encoded Gerber set.
Or you could import the -D gerbersand apeture list into a CAM package that can then output as -X version again.
Your problem is finding that program now.